The development of the skull of Psammophis sibilans . III. The osteocranium of a late embryo

The osteocranium of a late embryo of the Egyptian snake, Psammophis sibilans (age, 58 days; total body length, 190 mm) has been described. Attention was given to the relation of the different bones to the adjacent cartilages of the chondrocranium as well as to the topographical relation of the bones to each other in the late embryonic state. Several adjacent bones have not yet come in contact with each other. The membrane‐bones make their appearance shortly before any sign of ossification in the cartilaginous cranium. The maxillary, palatine and pterygoid premordia have a slight earlier appearance than the other bony premordia. The lacrymal, postfrontal, squamosal, jugal, quadratojugal and epipterygoid bones are completely absent. The laterosphenoid bone is never performed in cartilage. The whole columella auris is ossified.